Abstract: A cathode ray tube include phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes arranged in axially spaced relationship. The cathode structure includes a base metal having an electron emissive material coating and a heater for heating the base metal. The heater includes a major heating portion having a spirally wound heating wire and a pair of leg portions connected to opposite ends of the major heating portion. The major heating portion and an inner portion of each of the leg portions on a major-heating-portion side thereof are covered with an insulating coating, and the heater is welded to electrical conductors for applying a voltage thereto at an outer portion of each of the leg portions, the outer portion not being covered with the insulating coating.

Abstract: A cathode ray tube has a phosphor screen and an electron gun including an indirectly heated cathode structure and a plurality of electrodes disposed downstream of the indirectly heated cathode structure for projecting an electron beam toward the phosphor screen, and a deflection yoke for scanning the electron beam on the phosphor screen.

Abstract: A cathode ray tube includes a phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes arranged in axially spaced relationship. The cathode structure includes a base metal having an electron emissive material coating and a heater for heating the base metal. The heater includes a major heating portion having a spirally wound heating wire and a pair of leg portions connected to opposite ends of the major heating portion. The major heating portion and an inner portion of each of the leg portions on a major-heating-portion side thereof are covered with an insulating coating, and the heater is welded to electrical conductors for applying a voltage thereto at an outer portion of each of the leg portions, the outer portion not being covered with the insulating coating.

Abstract: A cathode ray tube includes a phosphor screen and an electron gun. The electron gun includes an indirectly heated cathode structure and plural grid electrodes in axially spaced relationship. The cathode structure includes a cap-shaped base metal having an electron emissive material coating and a heater for heating the cap-shaped base metal. The heater includes a major heating portion having a spirally wound heating wire and leg portions, and each of the leg portions includes a first multilayer winding portion having heating wires wound spirally in plural layers and a second multilayer winding portion intermediate between the major heating portion and the first multilayer winding portion and having heating wires wound in plural layers.

Abstract: A color cathode ray tube includes an electron gun having a plurality of cathodes and a cup-shaped first grid electrode spaced from the cathodes. The plurality of cathodes are supported within a plurality of eyelets corresponding to the number of the cathodes, respectively. The eyelets are disposed within and bonded to a tubular cathode support by bonding glass contained within the tubular cathode support, and satisfy the following relationship: (1.4 times a beam spacing S between two electron beams from the two adjacent cathodes divided by an outside radius of the eyelets-1.4 mm).gtoreq.(a height of the eyelets protruding beyond the top surface of the bonding glass).gtoreq.(0.98 times the beam spacing S divided by the outside radius of the eyelets-1.4 mm).

Abstract: A cathode-ray tube is provided with an electron gun having a cathode and a control electrode and some other electrodes. The cathode includes an electron emissive material layer for emission of electrons through a hole in the control electrode. The hole in the control electrode has a diameter substantially in a rage of from 0.3 mm to 0.4 mm. The electron emissive material layer has a first layer made of an oxide of an alkaline earth metal formed on a support and containing no oxide of a rare earth metal, and a second layer made of an oxide of an alkaline earth metal formed on the first layer and containing an oxide of a rare earth metal substantially in an amount of from 0.8 wt % to 5.0 wt %.

Abstract: A cathode for an electron tube has an electron emissive material layer on the surface of a cathode base metal. The electron emissive material layer has a three-layer structure composed of a first layer made of an alkaline earth metal oxide which is formed on the surface of the cathode base metal, a second layer which is an alkaline earth metal oxide layer in which a rare earth metal oxide is dispersed, which is formed on the surface of the first layer, and a third layer made of an alkaline earth metal oxide which is formed on the surface of the second layer.

Abstract: The present invention improves the stability among the qualities of the electron tube cathodes in which the barium scandate is dispersed and contained in the alkali earth metal oxide layer provided on the surface of the base metal, by making the shape and average particle size of the barium scandate similar to those of the carbonate used to form the alkali earth metal oxide, and it avoids the deterioration of the electron emission property for a long time, by setting the concentration of the barium scandate in the alkali earth metal oxide layer to zero at the position close to the surface of the base metal.

Abstract: The present invention relates to the manufacturing method of an indirectly heated cathode comprising the formation of a black film on the internal surface of a cathode sleeve, which contains a reducing material, the black film being formed by heat reduction of a thin film of a metal oxide, which has previously been formed on the internal surface of the cathode sleeve. The indirectly heated cathode manufactured by this method has shorter emission warm up time for the emission of electrons and lower power consumption compared with those manufactured by conventional methods.

Abstract: Three pipes for supporting three cathodes of an electron gun for an in-line type color cathode-ray tube parallel with one another in one and the same plane are arranged in one and the same plane, peripheral portions of the pipes are surrounded by a laterally extending cylindrical outer supporting frame extended in an arranging direction of the pipes through a fixing agent formed of crystallized hard glass powder with low melting point to fix the pipes, and a trapizoidal notch is provided upwardly of a lower side of the cylindrical outer supporting frame and along axes of the pipes to thereby prevent the pipes from being deformed.

Abstract: In a heater for an indirectly-heated cathode having a double helical structure, a film which can be removed by heating at the temperature of 250.degree. to 350.degree. C. is disposed between adjacent portions in a vertical direction, of a helical core wire coated with an insulating layer. Since this film is disposed, the occurrence of cracks in the insulating layer can be prevented so that the insulating property between the heater and a cathode sleeve do not gel deteriorated and clogging of an electron beam aperture of a shadow mask can be prevented, too.

Abstract: The improved structure of a heater for an indirectly-heated cathode which is used for CRTs or the like is disclosed. A core wire for a heater is wound around a mandrel into a primary winding so that the inner diameter of the primary winding is 4.3 to 6.0 times the diameter of the core wire. The primary winding may be further wound into a secondary winding.

Abstract: A dark heater is produced by a method which comprises coating the first coating layer made of an insulating material with a suspension containing heat-resistant particles having a high thermal emissivity, such as W particles, while 0.5 to 1.5 wt. % of a volatile matter such as water remains in the first coating layer to form a dark coating layer. Since the suspension having a low viscosity can be used, the thickness of the dark coating layer can be made highly uniform and the emission characteristics of the heater can be stabilized.

Abstract: Disclosed is a heater for indirect-heated cathode having a heating element composed of a wire with a high specific resistance, such as titanium or titanium-based alloy, around which another wire with a low specific resistance is wound, and having a heat-resisting insulating material covering at least part of said heating element.

Abstract: A color cathode ray tube wherein spring-back of a skirt of a shadow mask which causes the distortion of apertures of the shadow mask is prevented. The shadow mask is formed to exhibit a radius of curvature on an opposing pair of edges thereof. The shadow mask may be formed to exhibit a radius of curvature on four opposing edges. The radius of curvature is substantially equal to a radius of curvature of an apertured area of the shadow mask.